Effect of fluorine substitution, pressure and temperature on the tautomeric equilibria of acetylacetonate β-diketones

The equilibrium between the keto and enol tautomers of acetylacetone, trifluoroacetylacetone and hexafluoroacetylacetone in the neat liquid state and dissolved in supercritical fluid carbon dioxide have been studied, as a function of pressure and temperature, by 1 H NMR. This allows determination of the thermodynamic parameters, ΔH and ΔS, for the keto–enol equilibrium. The observed trends are well correlated with extraction results for this class of compounds.